The main factors contributing to "mushrooming" are the choice of wick (type and size), the fuel (wax) and what has been put into the fuel. EcoSoya™ waxes themselves burn exceptionally clean. Adding scent and dye to the wax "contaminates" the combustion process of a candle. Scent and color are non-fuel sources which can collect in the wick creating the "mushroom" or carbon ball you see. Changing the wick, scent and dye combination will correct this problem. We recommend using NON-cored wicks only.